Purpose :
Impaired dark adaptation (DA) is the earliest clinical marker of age-related macular degeneration (AMD). A prospective study of approximately 100 patients without a diagnosis of AMD was conducted to determine the prevalence of subclinical AMD in a general ophthalmology practice. The secondary aim to determine whether the prevalence of subclinical AMD was different in patients with and without a family history of AMD.

Methods :
Patients without a diagnosis of AMD, age of 60 years and older, were enrolled in the study. Subclinical AMD was defined as impaired DA, and was measured by calculating the rod intercept (RI) using MacuLogix’s AdaptDx rapid protocol as a screening test. If the RI was greater than 6.5 minutes, DA was considered impaired. Two groups of patients were enrolled: patients with a family history (FH group) and patients without a FH (NoFA group).

Results :
The sample consisted of 95 patients (NoFH = 50; FH = 45). The prevalence of impaired DA for the NoFH group 60% (30/50). The prevalence of impaired DA for the FH group was 62% (28/45). The mean age of each group was 69.5 years.

Conclusions :
In this routine anterior segment clinical practice, the prevalence of subclinical AMD was strikingly higher (60%) than the population-based estimate of prevalence (12.5%). Unexpectedly, the prevalence of the FH group was not greater than the NoFH group. One possible explanation is that there was unreliable reporting of family histories. Another potential explanation is selection bias by the members of NoFH group. A very interesting possibility is that the prevalence of AMD is significantly underestimated. Future studies may shed light on each of these hypotheses.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.